A novel fluorochrome for the microscopic observation of microbial morphology in wet mounts

A family of novel nontoxic fluorochromes, including trans-4-(p-N,N-dimethylaminostyryl)-N-butoxycarbonyl-methylpyridin ium bromide and other dimethylaminostyrylpyridinium salts, has been used for the examination of microorganisms in the living state. Equipment required is similar to that for immunofluorescence, but the technique does not necessitate the utilization of specific antibodies. Procaryotic vegetative cells and endospores were readily visualized by their fluorescence with no observable quenching. Other bacteria observed included capsule-forming species, acid-fast mycobacteria, and spirochetes. In addition, the technique is also applicable to the examination of eucaryotic microorganisms. The technique as described is simple and convenient, and serves as an alternate means for the microscopic study of viable microorganisms.